114 mytilidjE. 



scription agrees ad amussim with trie common shell which 

 is usually regarded as M. modiolus, the animal of which 

 he says is eaten in Norway. According to Lamarck, his 

 Modiola tulipa inhabits " les mers d'Amerique." Our 

 shell is the Modiola vulgaris of Fleming. The young is 

 the Mytilus curtus of Pennant and the Modiola barbata 

 of Macgillivray. 



3. M. barba'tus #j Linne. 



M. barbatv.s, Linn. Syst. Nat. p. 1156. Modiola barbata, F. & H. ii. p. 190, 

 pi. xliv. f. 4. 



Body reddish-brown : mantle not folded : gills narrow, 

 coarsely pectinated ; lower pair more than twice the depth of 

 the upper ones. 



Shell irregularly triangular, pointed at the smaller end and 

 expanding obliquely outward to a broad and obtusely rounded 

 edge in front, compressed, but gibbous towards the beaks, solid, 

 somewhat glossy on the upper part, but elsewhere of a dull 

 hue owing to the close investment of the bearded epidermis : 

 sculpture, numerous concentric membranaceous ridges : colour 

 yellowish-red, or scarlet: epidermis thick, yellowish-brown, 

 minutely but deeply striated lengthwise, thickly foliated, and 

 rising on the posterior side and in front into a fringe of thorn - 

 like projections, which are distinctly serrated or barbed on the 

 side facing the ventral portion ; the epidermis is reflected over 

 the front edge and forms a glistening band inside it : margins 

 thick, straight or incurved on the ventral side, angulated 

 behind, and obtusely rounded in front : byssal sinus large and 

 rather long : beaks small, close together, incurved, placed (as 

 in M. edulis) very near the point of the shell: hinge-liiie 

 straight, occupying about one-half of the dorsal margin : liga- 

 ment narrow, much sunk: hinge-plate thick, deeply grooved 

 for the reception of the ligament : hinge toothless, reflected : 

 inside highly nacreous and iridescent, sometimes beautifully 

 stained with purple on the posterior side and occasionally 

 studded with sessile pearls : muscidar scars indistinct : pallia! 

 scar well defined. L. 1*8. B. 1. 



Yar. oblonga. Shell more elongated and tumid ; ventral 



* Bearded. 



